Mineral chemistry of late Variscan gabbros from central Spain: constraints on crystallisation processes and nature of the parental magmas

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Petrología y geoquímica de las tonalitas de Villarejo de Montalbán

[ES] Las tonalitas de Villarejo de Montalbán son rocas ricas en biotita en las que se observan segregados más félsicos con abundante titanita. Los datos geoquímicos e isotópicos de roca total ((87Sr/86Sr)300 = 0,7084-0,7089; εNd = -4,79, -4,80) sugieren que el magma tonalítico se formó por fusión de rocas metaígneas de composición básica/intermedia (anfibolitas o granulitas). A su vez, los segregados félsicos parecen haberse formado por acumulación del magma residual diferenciado a partir de una matriz formada sobre todo por plagioclasa y biotita. Las condiciones de cristalización estimadas por geotermobarometría del anfíbol indican temperaturas de 890- 920ºC, y presiones de 1,3-2,4 kbar, las cuales implican niveles aproximados de emplazamiento cercanos a los 5-10 km de profundidad. [EN] The tonalites of Villarejo de Montalbán are biotite-rich rocks showing felsic segregates with abundant titanite. Whole-rock geochemical and isotopic data ((87Sr/86Sr)300 = 0.7084-0.7089; εNd = -4.79, -4.80) suggest that the tonalitic magma was formed by melting of metaigneous rocks of basic/intermediate composition (amphibolites or granulites). At the same time, the felsic segregates seem to have formed through the accumulation of a differentiated residual magma after crystal fractionation of plagioclase and biotite. Crystallization conditions estimated according to amphibole geothermobarometry indicate temperatures between 890 and 920ºC, and pressures in the range 1.3-2.4 kbar, which is in accordance with an approximate emplacement level close to 5-10 km deep.Peer Reviewe

Alkaline monzo-syenitic porphyries from the Spanish Central System: relationship with the accompaning lamprophyres

The alkaline monzo-syenitic porphyries from the Spanish Central System (SCS) show a heterogeneous composition ranging from basic to acid terms which give rise to major and trace element compositional trends in accordance with fractional crystallization of amphibole, plagioclase, biotite, alkaline feldspar, Timagnetite and apatite. The whole-rock geochemistry of the basic porphyries shows clear similarities with respect to the SCS isotopically enriched alkaline lamprophyres, indicating that a genetic link between both groups of dykes might exist. This relationship would probably represent an origin of the monzo-syenitic porphyries after differentiation of parental lamprophyric magmas due to fractional crystallizatio

Lung cancer mortality in towns near paper, pulp and board industries in Spain: a point source pollution study

<p>Abstract</p> <p>Background</p> <p>This study sought to ascertain whether there might be excess lung cancer mortality among the population residing in the vicinity of Spanish paper and board industries which report their emissions to the European Pollutant Emission Register (EPER).</p> <p>Methods</p> <p>This was an ecological study that modelled the Standardised Mortality Ratio (SMR) for lung cancer in 8073 Spanish towns over the period 1994–2003. Population exposure to industrial pollution was estimated on the basis of distance from town of residence to pollution source. An exploratory, near-versus-far analysis was conducted, using mixed Poisson regression models and an analysis of the effect of municipal proximity within a 50-kilometre radius of each of the 18 installations.</p> <p>Results</p> <p>Results varied for the different facilities. In two instances there was an increasing mortality gradient with proximity to the installation, though this was exclusively observed among men.</p> <p>Conclusion</p> <p>The study of cancer mortality in areas surrounding pollutant foci is a useful tool for environmental surveillance, and serves to highlight areas of interest susceptible to being investigated by ad hoc studies. Despite present limitations, recognition is therefore due to the advance represented by publication of the EPER and the study of pollutant foci.</p

Petrology and geochemistry of tonalites fromVillarejo de Montalbán (Toledo)

The tonalites of Villarejo de Montalbán are biotite-rich rocks showing felsic segregates with abundant titanite. Whole-rock geochemical and isotopic data ((87Sr/86Sr)300 = 0.7084-0.7089; εNd = -4.79, -4.80) suggest that the tonalitic magma was formed by melting of metaigneous rocks of basic/intermediate composition (amphibolites or granulites). At the same time, the felsic segregates seem to have formed through the accumulation of a differentiated residual magma after crystal fractionation of plagioclase and biotite. Crystallization conditions estimated according to amphibole geothermobarometry indicate temperatures between 890 and 920ºC, and pressures in the range 1.3-2.4 kbar, which is in accordance with an approximate emplacement level close to 5-10 km deepLas tonalitas de Villarejo de Montalbán son rocas ricas en biotita en las que se observan segregados más félsicos con abundante titanita. Los datos geoquímicos e isotópicos de roca total ((87Sr/86Sr)300 = 0,7084-0,7089; εNd = -4,79, -4,80) sugieren que el magma tonalítico se formó por fusión de rocas metaígneas de composición básica/intermedia (anfibolitas o granulitas). A su vez, los segregados félsicos parecen haberse formado por acumulación del magma residual diferenciado a partir de una matriz formada sobre todo por plagioclasa y biotita. Las condiciones de cristalización estimadas por geotermobarometría del anfíbol indican temperaturas de 890- 920ºC, y presiones de 1,3-2,4 kbar, las cuales implican niveles aproximados de emplazamiento cercanos a los 5-10 km de profundida

Composition and evolution of the lithospheric mantle in central Spain: inferences from peridotite xenoliths from the Cenozoic Calatrava volcanic field

Spinel lherzolite xenoliths from the Cenozoic Calatrava volcanic field provide a sampling of the lithospheric mantle of central Spain. The xenoliths are estimated to originate from depths of 35–50 km. Trace element content of clinopyroxene and Cr-number in spinel indicate low degrees of partial melting (5%) of the xenoliths. Although a major element whole-rock model suggests wider degrees of melting, the Calatrava peridotite chemistry indicates a moderately fertile mantle beneath central Spain. Calatrava peridotite xenoliths bear evidence for interaction with two different metasomatic agents. The enrichment in LREE (light rare earth element), Th, U and Pb, and the negative anomalies in Nb–Ta in clinopyroxene and amphibole from xenoliths of El Aprisco, indicate that the metasomatic agent was probably a subduction-related melt, whereas the enrichment in MREE in clinopyroxene from xenoliths of the Cerro Pelado centre suggests an alkaline melt similar to the host undersaturated magmas. These metasomatic agents are also consistent with the chemistry of interstitial glasses found in xenoliths of the two volcanic centres. Differences in metasomatism but also in mantle composition is supported by Sr–Nd whole-rock data, which show a more radiogenic nature for Sr isotopes of samples from the El Aprisco centre (87Sr/86Sr ratios of 0.7035–0.7044 instead of 0.7032–0.7037 for samples from Cerro Pelado). The timing of the subduction-related metasomatic stage is unconstrained, although the Calatrava intraplate volcanism intrudes an old Variscan lithospheric section reworked during the converging plate system affecting SE Iberia in the Tertiary. The presence of wehrlite types within the Calatrava peridotite xenoliths is here interpreted as a reaction of host lherzolites with silica-undersaturated silicate melts that could be related to the Calatrava alkaline magmatism. The Sr–Nd isotopic composition of Calatrava peridotites plot within the European asthenospheric reservoir (EAR) mantle, these values represent more enriched signatures than those found in the other Spanish Cenozoic alkaline province of Olot

The Variscan gabbros from the Spanish Central System: A case for crustal recycling in the sub-continental lithospheric mantle?

15 páginas, 12 figuras, 4 tablas.-- El Pdf del artículo es la versión post-print.The gabbroic intrusions that crop out along the Spanish Central System (SCS) are geochemically heterogeneous, including primitive and evolved rocks. Differentiation is mainly related to fractionation of Cr-spinel and olivine, but mixing with coeval granitic magmas or crustal assimilation may have also played a role in the evolution of the most differentiated rocks. The most primitive uncontaminated gabbros show arc-like trace element chondrite and primitive-mantle normalised patterns, characterised by large ion lithophile elements (LILE)-light rare earth elements (LREE) enrichment, Sr and Pb positive and Nb–Ta–Ti negative anomalies. However, paleogeographic constraints suggest that the SCS was located far from subduction zones, so these geochemical signatures could be better explained by a recycling of continental crustal components within the mantle. The most primitive SCS gabbros expand the Sr–Nd isotopic compositional range of the Variscan basic magmatism in the Central Iberian Zone to more depleted values. This reflects a heterogeneous sub-continental lithospheric mantle under central Spain ranging from a depleted mantle (εNd = + 3.1, 87Sr/86Sr = 0.704) towards an isotopically enriched component (εNd = − 1.6, 87Sr/86Sr = 0.706). Geochemical modelling suggests that mantle enrichment could be explained by minor lower crustal metapelitic granulite contamination (~ 2%). Additionally, the Sr–Nd–Pb isotopic ratios of the most primitive gabbros match the composition of the European subcontinental lithospheric mantle recorded in ultramafic xenoliths from western and central Europe.This work is included in the objectives of, and supported by, the CGL-2008-05952 project of the Ministerio de Educación y Ciencia of Spain and the CCG07-UCM/AMB-2652 project of the Complutense University of Madrid.Peer reviewe